4. The following reaction has been proposed as a possible route of NH3 synthesis in biological systems. 1/2 N2(g) + 3/2 H2O(g) -> NH3(g) + 3/4 O2(g) a) Use standard enthalpies of formation to calculate the standard enthalpy change for this reaction at 298.15K b) Assuming all gases are perfect, calculate the standard internal energy change for this reaction from the standard enthalpy change calculated in part a. c) Using mean bond energies, estimate the internal energy change for this reaction at 298K (in kJ/mole) d) Compare your two answers for the internal energy change (b and c). Which value should be closest to the value obtained from a calorimetry experiment? Explain.
6. 1,2 butadiene (H2C=C=CH-CH3) is sued in the production of synthetic rubber. It has a standard boiling point of 10.9 degrees celcius and an enthalpy of vaporization of 23.21 kJ/mole at 25 degrees celcius. (Note it is a gas at 1 bar pressure and 25 degrees celcius.) Like all hydrocarbons it is also a fuel.
a) Write and balance the chemical equation for the complete combustion of 1,2-butadiene. Assume the only chemical products are liquid water and CO2 gas. Don’t forget subscripts indicating states!
b) In order to determine the energy of combustion, a 1.015g sample of 1,2-butadiene underwent complete combustion in an adiabatic bomb calorimeter that had a calorimeter constant of 1950 J/K. This resulted in a temperature rise of 5.21K in the 1800g of water in the inner bath of the calorimeter. Use this data to calculate the internal energy of combustion for 1,2-butadiene (in kJ per mole fuel).
c) Using the answer obtained from part b, calculate the enthalpy of combustion of 1,2-butadiene (in kJ/mole) at 298.15K.
d) The difference in constant pressure heat capacities (Cp) for the above reaction is around 133J/K. (Assume this value is independent of T.) This means that, upon a 20 K rise in temperature, the enthalpy of combustion for 1,2-butadiene will *pick one* (greatly increase, slightly increase, not change, slightly decrease, greatly decrease). NOTE: “slightly” refers to a change of less than 5%, and “not change” of less than 0.1%.
7. I deal gas mixture
3.5 g of N2 and 3.5 g of O2 are placed in a 2.00 dm3 flask at 293.1 K. Assume ideal behaviour
a) Partial pressure of
8. For gases/ molar volume (Vm) is a function of temperature and pressure; that is Vm(T,P)
a) write a general expression of the differential dVm in terms of Dt,Dp,and the appropriate partial derivatices of Vm